body{
    width: 100%;
    min-width:320px;
    max-width: 640px;
    margin: 0px auto;
    font-size: 14px;
    color: #fff;
    background-color: #fff;
    font-family: -apple-system,Helvetica, sans-serif;
    line-height: 1.5;
}
*{
    -webkit-tap-highlight-color: transparent;
}
input{
    -webkit-appearance: none;
}
img,a{
    -webkit-touch-callout: none;
}
:focus{
    outline:none
}
.app{
    height: 45px;
}
ul{
    list-style: none;
    margin: 0;
    padding: 0;
}
.app ul li{
    float: left;
    height: 45px;
    background-color: #333;
    text-align: center;
    line-height: 45px;
}
.app ul li:nth-child(1){
    width: 8%;
}
.app ul li:nth-child(1) img{
    width: 10px;
}
.app ul li:nth-child(2){
    width: 10%;
}
.app ul li:nth-child(2) img{
    width: 30px;
    vertical-align: middle;
}
.app ul li:nth-child(3){
    width: 57%;
}
.app ul li:nth-child(4){
    width: 25%;
    background-color: #f63515;
}

.search_wrap{
    position:fixed;
    overflow: hidden;
    width: 100%;
    min-width: 320px;
    max-width: 640px;
    height: 44px;
}
.search_wrap .lf{
    position: absolute;
    left: 0;
    top: 0;
    width: 40px;
    height: 44px;
}
.lf::before{
    content: "";
    display: block;
    width: 20px;
    height: 18px;
    background: url(../study_36/p418.png) no-repeat;
    background-size: 20px 18px;
    margin: 14px 0 0 15px;
}
.search_wrap .rg{
    position: absolute;
    right: 0;
    top: 0;
    width: 40px;
    height: 44px;
    color: #fff;
    line-height: 44px;
}
.search{
    position: relative;
    height: 30px;
    margin: 0px 50px;
    background-color:#fff;
    border-radius: 15px;
    top: 7px;
}
.jd{
    position: absolute;
    top: 10px;
    left: 10px; 
    width: 20px;
    height: 15px; 
    background: url(../study_36/下载.png) no-repeat;
    background-size: 20px 15px;
}
.jd::after{
    position: absolute;
    content: "";
    top: 0;
    right: -10px;
    width: 1px;
    height: 15px;
    background: #ccc;
}
.search_icon{
    width: 18px;
    height: 15px;
    background-image: url(https://st.360buyimg.com/so/images/search/jd-sprites.png?__inline=);
    position: absolute;
    background-size: 200px;
    background-position: -80px 0px;
    left: 45px;
    top: 10px;
}
.search_input{
    width: 100%;
    position: absolute;
    left: 0px;
    top: 0px;
    padding-left: 75px;
    box-sizing: border-box;
}
.search_input input{
    border: none;
    height: 30px;
    line-height: 30px;
    width: 100%;
    border-radius: 0px 30px 30px 0px;
    box-sizing: border-box;
}
.slider img{
    width: 100%;
}
.nav{
    margin-top: 5px;
}
.nav a{
    width: 20%;
    float: left;
    color: #666;
    text-align: center;
    text-decoration: none;
}
.nav a img{
    width: 40px;
    margin: 10px 0px;
}
.nav span{
    display: block;
    font-size: 12px;
}
.clear{
    clear: both;
}